[mythtv] Firewire STB keeps jumping ports in 0.21-fixes. Suggestions?

Simon Koch sfkoch at gmail.com
Fri Mar 14 20:54:30 UTC 2008


On Wed, Feb 20, 2008 at 4:29 PM, Steven Adeff <adeffs.mythtv at gmail.com>
wrote:

> On Feb 17, 2008 9:26 AM, William Munson <w.munson at comcast.net> wrote:
> >
> > Daniel Kristjansson wrote:
> > > On Sat, 2008-02-16 at 22:03 -0500, William Munson wrote:
> > >
> > >> First off, sorry to post this to the dev list however I have not
> gotten
> > >> any answers in the users list.
> > >>
> > >> I am testing the 0.21-fixes branch on ubuntu and am running into a
> > >> situation where if I accidentally tune a bad channel with my DCT6416
> STB
> > >> it will cause the STB to switch ports from 1 to 0 and back again. The
> > >> port is still stable and firewire_tester will still capture packets
> in
> > >> broadcast mode just fine however the backend does not realize that
> the
> > >> port has moved even though the UUID is still the same. Am I missing
> > >> something or is there a bug that causes the backend end to miss the
> fact
> > >> that the port has changed? What can I do to troubleshoot this and
> > >> provide more useful info?
> > >>
> > >
> > > LinuxFirewireDevice::UpdateDeviceListItem() should update the device
> > > list when there is a reset, and LinuxFirewireDevice::HandleBusReset()
> > > should reconnect the device when it calls iec61883_cmp_reconnect(),
> > > but it doesn't always work. The Linux firewire guys weren't too
> > > interested in fixing this driver problem when I discovered it (though
> > > they were helpful in many ways with the firewire code.) They were
> > > working on a new driver which I understand should be immune to these
> > > types of problems. I no longer use the firewire recorder, so this is
> > > not something I've looked into further.
> > >
> > > The OSX FirewireRecorder does recover in these instances. But it has
> > > it's own problems. The OSX driver devs decided to always issue a bus
> > > reset when an application starts or stops using firewire, so you end
> > > up losing portions of your recordings if you have more than one STB
> > > or have some other firewire devices on the same bus.
> > >
> > > The upshot is that AFAICT the bug is in the Linux Firewire drivers and
> > > not in MythTV; unless you track down the bug in the drivers yourself
> > > it is not likely to be fixed until the whole firewire driver stack is
> > > replaced with the next generation firewire stack. BUT, it has been a
> > > while since I've been on top of this so you might want to read up on
> > > the posts in the linux1394-devel at lists.sourceforge.net the next gen
> > > driver might be in a usable state at this point, or it might have been
> > > abandoned, and/or someone might have written some patches to fix the
> > > problem in the existing drivers.
> > >
> > > Searching the linux1394 mailing list for "bus reset" might give you
> > > something useful...
> > >
> > > -- Daniel
> > >
> > >
> >
> > Thank you for the info. One more question. Is there a location in the
> > database that stores the current port? I was thinking of writing a
> > channel change script that would take a look at plugreport on each
> > channel change and update the database before changing channels. If myth
> > looks at this variable when setting up a recording then I could
> > dynamically update things whenever I change channel. It would also allow
> > me to stabilize the connection if required. This looks to be easier than
> > trying to patch the ubuntu 1394 stack.
> >
> > TIA,
> > William
>
> I have a channel change script that uses the Firewire GUID for the box
> in question to change the channel. It doesn't affect the database but
> since I've started using it (to fix 0-byte recordings) I've yet to
> miss a firewire recording. The downside is you have to manually give
> mythtv-setup the GUID of the box in the channel changer field, but
> otherwise it works great.
>
> http://www.mythtv.org/wiki/index.php/User:Steveadeff#6200changer.sh
>
> --
> Steve
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> mythtv-dev at mythtv.org
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>

I have a similar script.  I made 2 wrappers around it, each with the GUID of
one of my cable boxes.  I found that slightly more convenient than typing
them in in mythtv-setup.

    Simon
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